A tape-winding method is one of conventional methods for waterproof sealing or insulation of a joint of wires or cables or for binding a plurality of wires or cables. However, the tape-winding method has poor workability and does not always provide sufficient protection for a long period of time and is therefore lacking in reliability.
Another method for binding a plurality of wires or cables comprises, as disclosed in JP-A-1-236268 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), providing a moisture-blocking arrangement for cables in a slit of a base material comprising a thermoplastic resin, making the base material into a coil, putting a heat-shrinkable sleeve on the coil, and heating the sleeve to shrink and to fluidize the base material in the sleeve thereby sealing the moisture-blocking arrangement. However, this method is poor in workability because insertion of the moisture-blocking arrangement into the base material requires much labor and time. Further, in the case where there is a great difference between the outer diameter of cables and the inner diameter of the heat-shrinkable sleeve to make a considerable gap therebetween, a possibility arises in that the thermoplastic resin does not thoroughly flow into the gap on heating and the gap remains unfilled, resulting in a failure of sufficient sealing.
Another method for waterproof sealing or insulation of the joint of wires or cables comprises, as disclosed in JP-B-6-6341 (the term "JP-B" as used herein means an "examined published Japanese patent application"), putting a sealant and a heat-shrinkable tube having a hot-melt adhesive layer on the joint and heating the tube to shrink and to fluidize the hot-melt adhesive thereby sealing the gap. Where there is a great difference between the outer diameter of cables to be sealed and the inner diameter of the heat-shrinkable tube to make a considerable gap therebetween, this method also involves a possibility in that the thermoplastic resin does not thoroughly flow into the gap on heating leaving the gap unfilled, resulting in a failure of sufficient sealing.
In order to avoid gap-formation between cables and a heat-shrinkable tube after shrinkage, it is preferred to increase the thickness of the hot-melt adhesive layer to sufficiently increase the amount of the adhesive which is fluidized on heating. However, a thermoplastic resin having high flowability has poor extrusion molding properties since it shows large variation in outer diameter, and the extruded tubing adheres to each other during the production.